Circulating water quality control system and method for indirect air cooling system

Abstract

The invention provides a circulating water quality control system and method for an indirect air cooling system. The circulating water quality control system comprises a circulating water supply mother pipe and a circulating water return mother pipe which are connected between a condenser and a cooling tower; a hot side inlet of the plate heat exchanger is connected with the circulating water supply main pipe, and a side inlet is connected with boiler make-up water raw water; one end of the circulating water bypass flow treatment unit is connected with a hot side outlet of the plate heat exchanger, and the other end of the circulating water bypass flow treatment unit is connected with the circulating water return mother pipe; one end of the boiler make-up water treatment unit is connected with a cold side outlet of the plate heat exchanger, and the other end is connected with a water outlet pipeline of the condenser; the plate heat exchanger heats raw water of boiler make-up water through circulating water of the circulating water supply main pipe, the cooled circulating water returns to the circulating water return main pipe, and the heated raw water enters the boiler make-up water treatment unit. The circulating water bypass flow system is arranged in the indirect air cooling system, heat of circulating water bypass flow is used for heating boiler make-up water through the plate heat exchanger, waste heat recycling is achieved, and energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power plant engineering, and further relates to a circulating water quality control system and method for an indirect air cooling system. BACKGROUND

[0002] At present, the indirect air cooling generator set is the mainstream unit in the northern water shortage area, and the water quality control of the closed circulating water is the core element of the cooling equipment of the indirect air cooling system, which removes the heat of the equipment through circulating flow to maintain the back pressure of the generator set. Due to the long-term operation of the closed circulating water, the oxygen and carbon dioxide seeped into the system will cause corrosion of steel and aluminum, and then the water quality will deteriorate. At present, there are three common methods, one is to extract part of the circulating water into the boiler feed water treatment system for treatment by using the standby capacity of the boiler feed water treatment system; the second is to set a temporary small mixed bed for side flow treatment of the circulating water; the third is to discharge a large amount of water when the water quality deteriorates and supplement fresh demineralized water.

[0003] The boiler feed water treatment system is a system for producing demineralized water, which provides demineralized water for the thermal system and the indirect air cooling system. Due to the requirements of the system equipment, the water needs to be heated to 20-25℃. At present, the common method is to use the auxiliary steam of the steam turbine as a heat source to perform water-steam heat exchange with the raw water of the boiler feed water through a tubular heat exchanger.

[0004] The standby capacity of the boiler feed water treatment system is used to treat part of the circulating water. This method cannot be continuously operated, otherwise it will affect the normal standby capacity of the boiler feed water treatment, and will cause the poisoning of the mixed bed resin of the boiler feed water, resulting in the deterioration of the feed water quality of the thermal system and endangering the safe and stable operation of the unit.

[0005] A temporary small mixed bed is set for side flow treatment of the circulating water. At present, there is no effective basis for the selection of the output size of the mixed bed. The mixed bed does not have a fixed resin regeneration system. Once the resin is invalid, it cannot be regenerated, and the mixed bed becomes a disposable device and cannot be continuously operated for a long time. In addition, there is no pre-iron removal equipment in the system. When the unit starts, there are more iron corrosion products in the circulating water, which can easily cause iron poisoning of the mixed bed resin, affect the desalination effect, and thus cause the water quality of the circulating water to be unqualified, resulting in corrosion of iron and aluminum in the circulating water system. In addition, since the circulating water is directly extracted into the small mixed bed for treatment, the water temperature of the circulating water can reach more than 60℃ during the high temperature period in summer, which will damage the resin and the rubber layer of the equipment, affecting the service life and the water quality.

[0006] When the circulating water quality deteriorates, the amount of blowdown is increased, and fresh demineralized water is supplemented, resulting in an increase in the water consumption of the circulating water, which affects the water consumption index of the generator set.

[0007] The boiler feedwater treatment system uses turbine auxiliary steam as a heat source. Due to the heat exchange between steam and water, the steam side temperature is relatively high, which often causes scale to form on the water side of the tubular heat exchanger in less than six months of operation, resulting in reduced heat exchange efficiency and increased heat loss. At the same time, using auxiliary steam as a heating source for feedwater consumes effective heat sources and causes energy waste. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a circulating water quality control system and method for an indirect air-cooled system. The system utilizes the heat from the bypass flow of circulating water to heat the raw water for boiler feedwater, thereby achieving waste heat recovery and utilization.

[0009] An indirect air-cooled system circulating water quality control system includes: The circulating water supply header and circulating water return header connect the condenser and the cooling tower; The plate heat exchanger has a hot-side inlet connected to the circulating water supply header and a cold-side inlet connected to the boiler feedwater source. The circulating water bypass treatment unit has its inlet connected to the hot-side outlet of the plate heat exchanger and its outlet connected to the circulating water return header. The boiler feedwater treatment unit has an inlet connected to the cold-side outlet of the plate heat exchanger and an outlet connected to the condenser's water outlet pipeline. The plate heat exchanger heats the raw water of the boiler feedwater through the circulating water supply header. The cooled circulating water returns to the circulating water return header, and the heated raw water enters the boiler feedwater treatment unit.

[0010] Optionally, the circulating water bypass treatment unit includes a fiber filter unit and a mixed ion exchanger arranged sequentially along the water flow direction, wherein: The fiber filtration unit has its inlet connected to the hot-side outlet pipe of the plate heat exchanger to remove suspended solid particles from the cooled circulating water. The mixed ion exchanger has its inlet connected to the outlet pipe of the fiber filtration unit and its outlet connected to the circulating water return main pipe. It removes salt ions from the circulating water after it has been treated by the fiber filtration unit and returns the circulating water to the circulating water return main pipe.

[0011] Optionally, the fiber filtration unit includes: A fiber filter, with its inlet connected to the hot-side outlet pipe of the plate heat exchanger, is used to remove suspended solid particles from the cooled circulating water. A clean water tank, with its inlet connected to the outlet pipe of the fiber filter, is used to store filtered circulating water. A clean water pump has its inlet connected to the outlet pipe of the clean water tank and its outlet connected to the inlet of the mixed ion exchanger, thereby pressurizing the circulating water treated by the fiber filter and introducing it into the mixed ion exchanger.

[0012] Optionally, the fiber filtration unit further includes: An iron ion detector is installed on the outlet pipe of the fiber filter; The circulating water bypass treatment unit also includes: The bypass switching valve has its inlet connected to the outlet pipe of the clean water pump and its outlet connected to the circulating water return main pipe. When the iron ion content in the water effluent from the fiber filter exceeds a preset value, the bypass switching valve is opened to allow the circulating water to bypass the mixed ion exchanger and directly enter the circulating water return main pipe.

[0013] Optionally, in the mixed ion exchanger, the volume ratio of cation exchange resin to anion exchange resin is 2:1.

[0014] Optionally, the fiber filtration unit further includes: Two pressure detection devices are respectively installed on the inlet and outlet pipes of the fiber filter; A turbidity detection device is installed on the outlet pipe of the fiber filter; The circulating water bypass treatment unit also includes: The bypass valve has its inlet connected to the inlet pipe of the fiber filter and its outlet connected to the outlet pipe of the clean water pump. When the pressure difference between the inlet and outlet circulating water of the fiber filter reaches a preset pressure difference or the turbidity of the outlet circulating water of the fiber filter reaches a preset turbidity value, the bypass valve and the bypass switching valve are opened, allowing the circulating water to bypass the fiber filter unit and the mixed ion exchanger and directly enter the circulating water return header.

[0015] Optionally, the circulating water quality control system for the indirect air-cooled system may also include: The diversion regulating valve has its inlet connected to the circulating water supply header and its outlet connected to the hot-side inlet pipe of the plate heat exchanger, so as to regulate the flow rate of circulating water from the circulating water supply header into the hot-side inlet of the plate heat exchanger. Two temperature detection devices are respectively installed on the hot-side inlet and outlet pipes of the plate heat exchanger; The bypass regulating valve has its inlet connected to the outlet pipe of the diversion regulating valve and its outlet connected to the inlet pipe of the circulating water bypass treatment unit. Specifically, when the circulating water temperature is lower than the preset temperature, the bypass regulating valve is closed or its valve is adjusted to increase the amount of circulating water entering the hot side of the plate heat exchanger; when the circulating water temperature is greater than or equal to the preset temperature, the bypass regulating valve is adjusted to increase the amount of circulating water entering the hot side of the plate heat exchanger.

[0016] Optionally, the diversion regulating valve adjusts the flow rate of the circulating water diverted from the circulating water supply header into the hot side inlet of the plate heat exchanger to 0.1% to 0.3% of the total circulating water flow rate.

[0017] Optionally, the circulating water quality control system for the indirect air-cooled system may also include: An acid-base regeneration device is connected to a mixed ion exchanger in the circulating water bypass treatment unit and a mixed ion exchanger in the boiler feedwater treatment unit, so that the acid-base regeneration device can perform regeneration operations on either mixed ion exchanger in a time-sharing manner.

[0018] Embodiments of the present invention also provide a method for controlling the circulating water quality of an indirect air-cooled system, applied to the circulating water quality control system of the indirect air-cooled system described above, the method comprising: A portion of the high-temperature circulating water is diverted from the main water supply pipe of the indirect air-cooled system; The high-temperature circulating water flows through the hot side of the plate heat exchanger and exchanges heat with the boiler feed water flowing through the cold side of the plate heat exchanger. The circulating water after heat exchange and cooling is sent to the circulating water bypass treatment unit for treatment, and the treated effluent is returned to the circulating water return header. The boiler feedwater, after being heated by heat exchange, is sent to the boiler feedwater treatment unit for treatment, and the treated demineralized water is then supplied to the condenser.

[0019] The above-described solution of the present invention has at least the following beneficial effects: The above-mentioned solution of the present invention sets up a bypass system in the circulating water pipeline between the condenser and the cooling tower, and uses the heat of the bypass circulating water to heat the boiler feed water through a plate heat exchanger, thereby realizing the recovery and utilization of waste heat and reducing energy consumption; and adopts a circulating water bypass treatment unit to treat the bypass circulating water for iron removal and desalination, thereby reducing the amount of circulating water reagents and fresh water replenishment. Attached Figure Description

[0020] Fig. 1 This is a schematic diagram of the structure of the circulating water quality control system of the indirect air-cooled system of the present invention; Fig. 2 This is a schematic diagram of the structure of the circulating water bypass treatment unit in the circulating water quality control system of the indirect air-cooled system of the present invention; Fig. 3 This is a schematic diagram of the circulation of circulating water in the circulating water quality control system of the indirect air-cooled system of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Cooling tower; 2. Condenser; 12. Circulating water return main pipe; 21. Circulating water supply main pipe; 22. Circulating water bypass pipe; 211. Diversion regulating valve; 3. Circulating water bypass treatment unit; 4. Boiler feed water treatment unit; 5. Plate heat exchanger; 51. Bypass regulating valve; 52. Temperature detection device; 6. Fiber filtration unit; 61. Fiber filter; 610. Pressure monitoring device; 62. Clean water tank; 63. Clean water pump; 64. Bypass valve; 7. Mixed ion exchanger; 71. Bypass switching valve; 8. Acid-base regeneration equipment. Detailed Implementation

[0022] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0023] like Figs. 1-3 As shown, an embodiment of the present invention proposes a circulating water quality control system for an indirect air-cooled system, including: a circulating water supply header 21 and a circulating water return header 12 connected between the condenser 2 and the cooling tower 1; The plate heat exchanger 5 has a hot-side inlet connected to the circulating water supply header 21 and a cold-side inlet connected to the boiler feedwater source. The inlet of the circulating water bypass treatment unit 3 is connected to the hot side outlet of the plate heat exchanger 5, and the outlet is connected to the circulating water return header 12. The boiler feedwater treatment unit 4 has its inlet connected to the cold side outlet of the plate heat exchanger 5 and its outlet connected to the water outlet pipeline of the condenser. The plate heat exchanger 5 heats the raw water of the boiler feedwater through the circulating water supply header 21. The cooled circulating water returns to the circulating water return header 12, and the heated raw water enters the boiler feedwater treatment unit 4.

[0024] In the circulating water quality control system of the indirect air-cooled system of this invention, the hot side of the plate heat exchanger 5 is connected in series between the circulating water supply header 21 and the circulating water return header 12, diverting part of the circulating water supply between the condenser 2 and the cooling tower 1 to form a circulating water bypass; the cold side of the plate heat exchanger 5 is connected in series between the raw water supply pipeline and the boiler feedwater treatment unit 4 to realize the coupling treatment and arrangement of the indirect air-cooled circulating bypass water and the boiler feedwater; the plate heat exchanger 5 uses the high-temperature circulating water in the hot-side circulating water supply header 21 to heat the raw water of the boiler feedwater, and at the same time, reduces the temperature of the circulating water. The cooled circulating water returns to the circulating water return header 12 through the circulating water bypass treatment unit 3, using the waste heat of the indirect air-cooled bypass circulating water as a heat source for heating the boiler feedwater, replacing new steam, reducing energy consumption and production costs, and improving energy utilization efficiency. Figs. 1-3 In the diagram, arrows indicate the direction of fluid flow. The system operation in this embodiment is continuous; the circulating water bypass and boiler feedwater are independent and do not affect each other, only exchanging heat. The heated raw water, after being treated by the boiler feedwater treatment unit 4, supplies demineralized water to the thermal system downstream of the condenser 2. The plate heat exchanger 5 is also connected in series with the circulating water bypass treatment unit 3. The circulating water first passes through the plate heat exchanger 5 to cool down before entering the circulating water bypass treatment unit 3 to remove suspended solid particles and desalinate, stabilizing the pH value of the circulating water. The circulating water bypass treatment unit 3 can remove both iron and salt, reducing the amount of chemicals added to the circulating water and the amount of fresh water replenished. Suspended solid particles include metal corrosion products.

[0025] In an optional embodiment of the present invention, the circulating water bypass treatment unit 3 includes a fiber filter unit 6 and a mixed ion exchanger 7 arranged sequentially along the water flow direction, wherein: The fiber filter unit 6 has its inlet connected to the hot-side outlet pipe of the plate heat exchanger 5 to remove suspended solid particles from the cooled circulating water. The mixed ion exchanger 7 has its inlet connected to the outlet pipe of the fiber filter unit 6 and its outlet connected to the circulating water return header 12. It removes salt ions from the circulating water after it has been treated by the fiber filter unit 6 and returns the circulating water to the circulating water return header 12.

[0026] In this embodiment, the fiber filtration unit 6 is located after the plate heat exchanger 5. The fiber filtration unit 6 removes suspended solid particles from the cooled circulating water. These suspended solid particles mainly include iron corrosion products, such as suspended rust particles, as well as corrosion products and impurities from other metals, such as copper and aluminum. After the fiber filtration unit 6 filters out large particulate impurities, the circulating water enters the mixed ion exchanger 7 for fine desalination. The mixed ion exchanger 7 is a mixed bed, in which cation exchange resin and anion exchange resin remove salt ions from the circulating water. The mixed bed is located after the fiber filtration unit 6 and receives circulating water that has already had solid rust removed and its temperature lowered.

[0027] In an optional embodiment of the present invention, the volume ratio of cation exchange resin to anion exchange resin in the mixed ion exchanger 7 is 2:1.

[0028] In this embodiment, the indirect air-cooled circulating water is typically maintained at a high pH (alkaline) for corrosion prevention. Alkaline water means there are more OH⁻ ions in the water, relatively fewer anions that need to be exchanged, and more cations that need to be neutralized (such as those causing hardness). The ratio of cation to anion resin is relatively high. Using a 2:1 ratio of cation to anion resin perfectly matches the characteristics of this water quality, allowing both resins to degrade simultaneously. This maximizes the operating cycle of the mixed bed, reduces regeneration frequency, and improves economic efficiency. The circulating water treated by the mixed bed contains almost no dissolved salts or ions. Replenishing this ultrapure water to the circulating water system significantly dilutes the overall salt content; stabilizes the pH value of the circulating water, reduces system corrosion tendency, prevents heat exchanger scaling, ensures heat exchange efficiency, and extends the operating cycle of the mixed bed.

[0029] like Fig. 2 As shown, in an optional embodiment of the present invention, the fiber filtration unit 6 includes: Fiber filter 61, with its inlet connected to the hot-side outlet pipe of the plate heat exchanger 5, is used to remove suspended solid particles from the cooled circulating water. The clean water tank 62 has its inlet connected to the outlet pipe of the fiber filter 61 to store the filtered circulating water; The clean water pump 63 has its inlet connected to the outlet pipe of the clean water tank 62 and its outlet connected to the inlet of the mixed ion exchanger 7, thereby pressurizing the circulating water treated by the fiber filter 61 into the mixed ion exchanger 7.

[0030] In this embodiment, Fig. 2The middle arrow indicates the fluid flow direction. Cooled circulating water flows sequentially through fiber filter 61 for filtration and treatment before entering the clear water tank 62 for buffering. It is then pressurized by the clear water pump 63 and enters the mixed ion exchanger 7. Fiber filter 61 primarily performs deep filtration of the circulating water, effectively trapping suspended solid particles and iron corrosion products (such as rust) using fiber filter media, thus protecting downstream precision equipment. Clear water tank 62 stores filtered clean water, balancing system water volume fluctuations and ensuring a stable and continuous water supply to subsequent treatment units. Clear water pump 63 provides the necessary pressure to ensure a stable delivery of water from clear water tank 62 to the subsequent mixed ion exchanger 7. The lower-temperature circulating water bypass reduces the damage to the filter element of fiber filter 61 and the resin of mixed ion exchanger 7 caused by high-temperature water, extending their service life.

[0031] In an optional embodiment of the present invention, the fiber filtration unit 6 further includes an iron ion detector, which is disposed on the outlet pipe of the fiber filter 61; The circulating water bypass treatment unit 3 further includes: The bypass switching valve 71 has its inlet connected to the outlet pipe of the clean water pump 63 and its outlet connected to the circulating water return main pipe 12. When the iron ion content in the water effluent from the fiber filter 61 exceeds a preset value, the bypass switching valve 71 is opened so that the circulating water bypasses the mixed ion exchanger 7 and directly enters the circulating water return main pipe 12.

[0032] In this embodiment, a bypass pipe is installed in parallel with the mixed ion exchanger 7, and a bypass switching valve 71 is installed on this bypass pipe. When the iron ion content of the water effluent from the fiber filter exceeds the standard, the bypass switching valve 71 of the mixed ion exchanger 7 is opened, and the pipe valve flowing through the mixed ion exchanger 7 is closed. The circulating water from the fiber filter 61 no longer enters the mixed ion exchanger 7, but directly flows through this bypass pipe into the circulating water return header 12, removing iron from the circulating water but not desalinizing it. If the iron ion content exceeds the preset value, it means that the upstream iron removal system has malfunctioned or reached its processing limit, and a large amount of dissolved iron ions have entered the subsequent pipeline. At this time, if this water with high iron content continues to enter the mixed ion exchanger 7 (mixed bed), it will lead to disastrous consequences. The iron ion content exceeds the standard, bypassing the mixed ion exchanger 7 to protect it. The bypass pipe of the mixed ion exchanger 7 ensures a continuous flow of water from the circulating water system, regardless of whether the mixed bed is in operation. This flow is uninterrupted even when the mixed bed is shut down, thus preventing flow shocks to the main circulating water system. Furthermore, when the mixed bed requires regeneration, maintenance, or if there is a risk to the quality of the influent, the upstream fiber filter unit 6 can continue operating, guaranteeing uninterrupted basic iron removal functionality.

[0033] In an optional embodiment of the present invention, the fiber filtration unit 6 further includes: Two pressure detection devices 610 are respectively installed on the inlet and outlet pipes of the fiber filter 61; A turbidity detection device is installed on the outlet pipe of the fiber filter 61; The circulating water bypass treatment unit 3 further includes: The bypass valve 64 is connected to the inlet pipe of the fiber filter 61 and the outlet pipe of the clean water pump 63. When the pressure difference between the inlet and outlet circulating water of the fiber filter 61 reaches a preset pressure difference or the turbidity of the outlet circulating water of the fiber filter 61 reaches a preset turbidity value, the bypass valve 64 and the bypass switching valve 71 are opened, so that the circulating water bypasses the fiber filter unit 6 and the mixed ion exchanger 7 and directly enters the circulating water return header 12.

[0034] In this embodiment, the fiber filter 61 is equipped with a differential pressure gauge at its inlet and outlet, and a turbidity meter at its outlet. When the inlet and outlet differential pressure or the turbidity meter reaches a set value, the fiber filter 61 exits the circulation system for backwashing. At the same time, the bypass switching valve 71 of the mixed bed bypass system is opened, and the circulating water directly flows into the circulating water return header 12, ensuring that the mixed bed values ​​are not contaminated. The outlet pipe of the clear water tank 62 is connected to the inlet of the backwash pipe, and the outlet of the backwash pipe is connected to the outlet pipe of the fiber filter 61. During backwashing, the valve of the circulating water entering the pipe before the fiber filter 61 is closed, and the valve of the circulating water entering the pipe before the mixed ion exchanger 7 is also closed to prevent circulating water from flowing into the fiber filter 61 and the ion exchanger 7. The bypass valves 64 and 71 of the bypass channels of the fiber filter unit 6 and the mixed ion exchanger 7 are opened respectively, and the clear water pump of the backwash pipe is turned on to draw buffered circulating water from the clear water tank 62 to remove suspended solid particles and rinse the fiber filter 61. After rinsing, the cleaning wastewater is discharged. When the fiber filter 61 is backwashed, the circulating water bypass treatment unit 3 continues to work, but iron removal and desalination are temporarily suspended. After cleaning, it will automatically resume operation, and the fiber filter 61 and the mild ion exchanger 7 will resume operation. This will not be elaborated here.

[0035] like Fig. 1 and Fig. 2 As shown, in an optional embodiment of the present invention, the system further includes: The diversion regulating valve 211 has its inlet connected to the circulating water supply header 21 and its outlet connected to the hot side inlet pipe of the plate heat exchanger 5, so as to regulate the flow rate of circulating water from the circulating water supply header 21 into the hot side of the plate heat exchanger 5. Two temperature detection devices 52 are respectively installed on the hot side inlet and outlet pipes of the plate heat exchanger 5; The bypass regulating valve 51 has its inlet connected to the outlet pipe of the diversion regulating valve 211, and its outlet connected to the inlet pipe of the circulating water bypass treatment unit 3. Specifically, when the circulating water temperature is lower than the preset temperature, the valve of the bypass regulating valve 51 is closed or adjusted to increase the amount of circulating water entering the hot side of the plate heat exchanger 5; when the circulating water temperature is greater than or equal to the preset temperature, the valve of the bypass regulating valve 51 is adjusted to decrease the amount of circulating water entering the hot side of the plate heat exchanger 5.

[0036] In this embodiment, a circulating water bypass pipe 22 is provided between the circulating water supply main pipe 21 and the circulating water return main pipe 12. The hot side of the plate heat exchanger 5 and the circulating water treatment unit 3 are connected in series on the circulating water bypass pipe. The diversion regulating valve 211 can be provided on the circulating water bypass pipe. By adjusting the opening of the diversion regulating valve 211, the circulating water volume in the diversion circulating water supply main pipe 21 is adjusted.

[0037] Pressure sensors 610 are also installed on the inlet and outlet pipes of the plate heat exchanger 5 on the hot side. The outlet of the plate heat exchanger 5 can share the pressure sensor 610 with the inlet of the fiber filter 61. Pressure sensors and temperature sensors are also installed on the inlet and outlet pipes of the plate heat exchanger 5 on the cold side. Simultaneously, the temperature and pressure of the circulating water and the temperature and pressure of the boiler feedwater are monitored before and after heat exchange through the plate heat exchanger 5. The raw water of the boiler feedwater treatment system, which serves as the cold source, can be heated to 20~25℃ after heat exchange through the heat exchanger, which can meet the temperature requirements of the boiler feedwater treatment unit. It should be noted that a bypass pipe is installed in parallel with plate heat exchanger 5. The inlet of the bypass pipe is connected to the inlet pipe on the hot side of plate heat exchanger 5, and the outlet of the bypass pipe is connected to the outlet pipe of plate heat exchanger 5. A bypass regulating valve 51 is installed on this bypass pipe. Automatic regulating valves and temperature and pressure sensors are installed at the inlet and outlet of the plate heat exchanger. When the circulating water temperature is low, the bypass regulating valve 51 is closed or its regulating valve is partially closed to increase the water exchange rate of the heat exchanger, ensuring that most of the water flows through plate heat exchanger 5 for sufficient cooling, and ensuring that the water entering the fiber... The water temperature in the filter 61 and the mixed ion exchanger 7 will not be too high, protecting the resin from being scalded. When the circulating water temperature is high, the bypass regulating valve 51 is opened wider to reduce the amount of hot water exchanged in the heat exchanger. This allows most of the high-temperature water to bypass the plate heat exchanger 5 and mix with the water cooled by the plate heat exchanger 5, reducing the load on the plate heat exchanger. This ensures that the boiler feedwater flowing through the cold side of the plate heat exchanger 5 can still be fully heated to the required temperature, stabilizing the water temperature entering the mixed bed and preventing temperature fluctuations from affecting the ion exchange efficiency. This ensures stable heat transfer and automated system operation.

[0038] In an optional embodiment of the present invention, the diversion regulating valve 211 regulates the flow rate of the circulating water diverted from the circulating water supply header 21 into the hot side inlet of the plate heat exchanger 5 to be 0.1% to 0.3% of the total circulating water flow rate.

[0039] In this embodiment, a circulation pump can also be installed in the circulating water bypass pipeline. The circulation pump can work in conjunction with the diversion regulating valve 211 to divert a small portion of the circulating water in the circulating water supply main pipe 21, thereby achieving the complete treatment of all circulating water within the shortest corrosion cycle of the aluminum heat exchanger.

[0040] like Fig. 1 As shown, in an optional embodiment of the present invention, the circulating water quality control system of the indirect air-cooled system further includes: an acid-base regeneration device 8, which is connected to the mixed ion exchanger 7 in the circulating water bypass treatment unit 3 and the mixed ion exchanger in the boiler feedwater treatment unit 4, so that the acid-base regeneration device can perform regeneration operations on any mixed ion exchanger in a time-sharing manner.

[0041] The boiler feedwater treatment unit 4 in this embodiment includes: a pretreatment unit, a reverse osmosis membrane, a decarbonator, a mixed ion exchanger, and an ultrapure demineralized water unit. The raw water for the boiler feedwater treatment unit 4 can be tap water or river water, which has a lower temperature. This raw water serves as the cold source for the plate heat exchanger 5, used to cool the high-temperature circulating bypass water. The raw water first flows through the plate heat exchanger 5 and is heated to a preset temperature range. Then it enters the boiler feedwater treatment unit, sequentially flowing through the pretreatment unit. The pretreatment unit filters and softens the raw water, which then sequentially flows through the reverse osmosis membrane for desalination, the decarbonator for carbon dioxide removal, the mixed bed for deep desalination, and the ultrapure demineralized water unit for polishing to obtain ultrapure water, which is then supplied to the backup thermal system.

[0042] The mixed ion exchanger 7 in the circulating water bypass treatment unit 3 shares an acid-base regeneration device 8 with the mixed ion exchanger in the boiler feedwater unit 4. This integrates the circulating water bypass treatment system and the boiler feedwater treatment system, ensuring that the mixed ion exchangers in both units share the same acid-base regeneration device; no separate regeneration device is provided for the mixed bed in the circulating water bypass treatment unit. The circulating water bypass treatment unit 3 also shares a compressed air unit with the boiler feedwater unit 4 for compressed air, and an acid and alkali system with the boiler feedwater unit 4 for regeneration of acid and alkali solutions.

[0043] The embodiments of the present invention, through the coupled arrangement of circulating water bypass water and boiler feed water, can share the acid and alkali regeneration system and compressed air system, reduce equipment footprint, and at the same time enable the circulating water bypass treatment system to operate continuously, ensuring the water quality of the circulating water.

[0044] This invention also proposes a method for controlling the circulating water quality of an indirect air-cooled system, employing an indirect air-cooled system circulating water quality control system as described above, comprising: Step S10: Divert a portion of the high-temperature circulating water from the circulating water supply header 21 of the indirect air-cooling system; Step S20: The high-temperature circulating water flows through the hot side of the plate heat exchanger 5 and exchanges heat with the boiler feed water flowing through the cold side of the plate heat exchanger 5. Step S30: The circulating water after heat exchange and cooling is sent to the circulating water bypass treatment unit 3 for treatment, and the treated effluent is returned to the circulating water return header 12. Step S40: The boiler feedwater raw water after heat exchange and heating is sent to the boiler feedwater treatment unit 4 for treatment, and the treated demineralized water is supplied to the condenser 2.

[0045] In this embodiment of the invention, the temperature of the inlet and outlet of the plate heat exchanger 5 on the hot side can be monitored, and the opening of the regulating valve and bypass regulating valve on its pipeline can be dynamically adjusted to control the inlet water temperature of the circulating water bypass treatment unit 3 to be stable within a preset range.

[0046] It should be noted that all the implementation methods in the above system are applicable to this method and can achieve the same technical effect.

[0047] The system and method of the present invention extract a portion of the high-temperature circulating water at a rate of 0.1% to 0.3% of the circulating water flow rate and introduce it into the circulating water bypass system. First, the circulating water enters a plate heat exchanger to lower its temperature. The cold source is the raw water from the boiler feedwater treatment system. After cooling, the circulating water enters a fiber filter, is treated, and then enters a clear water tank for buffering. It is then pressurized by a clear water pump and enters a mixed ion exchanger. The resin ratio of the mixed ion exchanger is selected at a 2:1 cation-to-cation ratio. The effluent from the mixed ion exchanger returns to the circulating water return header. When the iron ion content in the effluent from the fiber filter exceeds the standard, the bypass automatic valve of the mixed ion exchanger is opened to remove only iron (treated by the fiber filter), without desalination.

[0048] The raw water in the boiler feedwater treatment system, which serves as a cold source, is heated to 20-25°C after passing through a heat exchanger, which meets the temperature requirements of the boiler feedwater treatment system.

[0049] The plate heat exchanger is equipped with automatic regulating valves and temperature and pressure sensors at the inlet and outlet. It is also equipped with a bypass automatic regulating valve. When the circulating water temperature is low, the bypass valve is closed or the regulating valve is closed slightly to increase the amount of hot water exchanged by the heat exchanger. When the circulating water temperature is high, the bypass valve is opened wider to reduce the amount of hot water exchanged by the heat exchanger, thereby ensuring stable heat transfer and automated system operation.

[0050] The fiber filter is equipped with a differential pressure gauge at the inlet and outlet and a turbidity meter at the outlet. When the inlet and outlet differential pressure or the turbidity meter reaches the set value, the system is shut down for backwashing. At the same time, the mixed bed bypass system is opened to ensure that the mixed bed values ​​are not contaminated.

[0051] Based on the characteristics of circulating water, it is proposed that the mixed bed resin ratio be designed at 2:1 (cation:coagulation) to extend the operating cycle of the mixed bed.

[0052] The circulating water bypass treatment system is integrated with the boiler feedwater treatment system, and the acid and alkali regeneration equipment is shared with the feedwater treatment system. The regeneration equipment for the mixed bed of the circulating water bypass treatment system is not set up separately.

[0053] The above-mentioned solution of the present invention can achieve both iron removal and desalination, and achieve continuous and stable operation, removing metal corrosion products from circulating water, stabilizing pH value, and reducing the amount of reagents and fresh water replenishment. Coupling and arranging the indirect cooling bypass water with the boiler feedwater allows the waste heat of the indirect cooling bypass circulating water to be used as a heat source for heating the boiler feedwater, replacing fresh steam, reducing energy consumption and production costs, and improving energy utilization efficiency. Through the coupled arrangement of the circulating water bypass water and the boiler feedwater, the acid-base regeneration system and compressed air system can be shared, reducing equipment footprint. Simultaneously, the circulating water bypass treatment system can operate continuously, ensuring the water quality of the circulating water. Lowering the temperature of the circulating water bypass water reduces the damage of high-temperature water to the filter elements and resin in the bypass treatment system, extending the service life of the filter elements and resin.

[0054] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A circulating water quality control system for an indirect air-cooled system, characterized in that, include: A circulating water supply header (21) and a circulating water return header (12) are connected between the condenser (2) and the cooling tower (1). The plate heat exchanger (5) has its hot side inlet connected to the circulating water supply header (21) and its cold side inlet connected to the boiler feedwater source. The inlet of the circulating water bypass treatment unit (3) is connected to the hot side outlet of the plate heat exchanger (5), and the outlet is connected to the circulating water return header (12). The boiler feedwater treatment unit (4) has its inlet connected to the cold side outlet of the plate heat exchanger (5) and its outlet connected to the water outlet pipeline of the condenser. The plate heat exchanger (5) heats the raw water of the boiler feedwater through the circulating water supply header (21), and the cooled circulating water returns to the circulating water return header (12), while the heated raw water enters the boiler feedwater treatment unit (4).

2. The circulating water quality control system for the indirect air-cooled system according to claim 1, characterized in that, The circulating water bypass treatment unit (3) includes a fiber filter unit (6) and a mixed ion exchanger (7) arranged sequentially along the water flow direction, wherein: The fiber filter unit (6) is connected at its inlet to the hot side outlet pipe of the plate heat exchanger (5) to remove suspended solid particles from the cooled circulating water. The mixed ion exchanger (7) has its inlet connected to the outlet of the fiber filter unit (6) and its outlet connected to the circulating water return header (12). It removes salt ions from the circulating water after it has been treated by the fiber filter unit (6) and returns the circulating water to the circulating water return header (12).

3. The circulating water quality control system for the indirect air-cooled system according to claim 2, characterized in that, The fiber filtration unit (6) includes: The fiber filter (61) is connected at its inlet to the hot-side outlet pipe of the plate heat exchanger (5) to remove suspended solid particles from the cooled circulating water. The inlet of the clean water tank (62) is connected to the outlet pipe of the fiber filter (61) to store the filtered circulating water; The inlet of the water pump (63) is connected to the outlet pipe of the water tank (62), and the outlet is connected to the inlet of the mixed ion exchanger (7), which pressurizes the circulating water treated by the fiber filter (61) and puts it into the mixed ion exchanger (7).

4. The circulating water quality control system for the indirect air-cooled system according to claim 3, characterized in that, The fiber filtration unit (6) further includes: An iron ion detector is installed on the outlet pipe of the fiber filter (61); The circulating water bypass treatment unit (3) also includes: The bypass switching valve (71) is connected at its inlet to the outlet pipe of the water pump (63) and at its outlet to the circulating water return main pipe (12). When the iron ion concentration in the water effluent from the fiber filter (61) exceeds a preset value, the bypass switching valve (71) is opened so that the circulating water bypasses the mixed ion exchanger (7) and directly enters the circulating water return main pipe (12).

5. The circulating water quality control system for the indirect air-cooled system according to claim 2, characterized in that, In the mixed ion exchanger (7), the volume ratio of cation exchange resin to anion exchange resin is 2:

1.

6. The circulating water quality control system for the indirect air-cooled system according to claim 4, characterized in that, The fiber filtration unit (6) further includes: Two pressure detection devices (610) are respectively installed on the inlet and outlet pipes of the fiber filter (61); A turbidity detection device is installed on the outlet pipe of the fiber filter (61); The circulating water bypass treatment unit (3) also includes: The bypass valve (64) is connected to the inlet pipe of the fiber filter (61) and the outlet pipe of the clean water pump (63). When the pressure difference between the inlet and outlet circulating water of the fiber filter (61) reaches the preset pressure difference or the turbidity of the outlet circulating water of the fiber filter (61) reaches the preset turbidity value, the bypass valve (64) and the bypass switching valve (71) are opened, so that the circulating water bypasses the fiber filter unit (6) and the mixed ion exchanger (7) and directly enters the circulating water return header (12).

7. The circulating water quality control system for the indirect air-cooled system according to claim 1, characterized in that, Also includes: The diversion regulating valve (211) has its inlet connected to the circulating water supply header (21) and its outlet connected to the hot side inlet pipe of the plate heat exchanger (5) to regulate the flow rate of the circulating water from the circulating water supply header (21) into the hot side inlet of the plate heat exchanger (5). Two temperature detection devices (52) are respectively installed on the hot side inlet and outlet pipes of the plate heat exchanger (5); The bypass regulating valve (51) has its inlet connected to the outlet pipe of the diversion regulating valve (211) and its outlet connected to the inlet pipe of the circulating water bypass treatment unit (3). When the circulating water temperature is lower than the preset temperature, the valve of the bypass regulating valve (51) is closed or reduced to increase the amount of circulating water entering the hot side of the plate heat exchanger (5). When the circulating water temperature is greater than or equal to the preset temperature, the valve of the bypass regulating valve (51) is increased to reduce the amount of circulating water entering the hot side of the plate heat exchanger (5).

8. The circulating water quality control system for the indirect air-cooled system according to claim 7, characterized in that, The diversion regulating valve (211) regulates the flow rate of circulating water diverted from the circulating water supply header (21) into the hot side inlet of the plate heat exchanger (5) to be 0.1% to 0.3% of the total circulating water flow rate.

9. The circulating water quality control system for the indirect air-cooled system according to claim 2, characterized in that, Also includes: An acid-base regeneration device (8) is connected to the mixed ion exchanger (7) in the circulating water bypass treatment unit (3) and the mixed ion exchanger in the boiler feedwater treatment unit (4), so that the acid-base regeneration device can perform regeneration operations on any mixed ion exchanger in a time-sharing manner.

10. A method for controlling the circulating water quality of an indirect air-cooled system, characterized in that, The indirect air-cooled system circulating water quality control system according to any one of claims 1 to 9 includes: A portion of the high-temperature circulating water is diverted from the circulating water supply header (21) of the indirect air-cooled system; The high-temperature circulating water flows through the hot side of the plate heat exchanger (5) and exchanges heat with the boiler feed water flowing through the cold side of the plate heat exchanger (5). The circulating water after heat exchange and cooling is sent to the circulating water bypass treatment unit (3) for treatment, and the treated effluent is returned to the circulating water return header (12). The boiler feedwater after heat exchange and heating is sent to the boiler feedwater treatment unit (4) for treatment, and the treated demineralized water is supplied to the condenser (2).

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